A new generation of telephone sets has emerged, termed "smart" telephones. Such smart telephones are highly sophisticated, including program controlled processors to automatically carry out communication functions where such functions where heretofore completed only by the intervention of a person manipulating the controls of the telephone. For example, the on-hook and off-hook functions of standard telephones are controlled by the physical placement of a handset on or off the hook switch of the telephone. In addition, in completing outgoing telephone calls, the outpulsing of digits, and especially those requiring the intervention long-distance common carriers, is automatically accomplished by repeating the digits input by the calling party, in addition to other digit strings irrespective of whether such call can be completed via a particular common carrier. Many of these functions are transparent to the user.
Standard telephones and smart telephones are typically powered by central office battery, via a tip-and-ring subscriber line. However, such battery power is not available to the circuits of the telephone set during on-hook conditions, as the hook switch then disconnects the subscriber line from the telephone circuits. This is disadvantageous in situations where circuit operations of the telephone are required during on-hook conditions. While the telephone sets could be constructed with internal battery supplies to power the circuits during on-hook situations, such an approach is not preferable, due to the cost of the batteries and recharging circuits, as well as the space required to accommodate such additional components.
In addition to the enhanced sophistication of telephones themselves, the environment in which telephones must operate has also become much more complicated. For instance, regulatory constraints impose strict territorial limitations on the various common carriers. In other words, a person is not without unlimited options in employing common carriers of choice to complete telephone calls to certain destinations. In particular, and as a result of recent impositions of territorial restrictions by the courts, local access transport areas (LATA) have been established in which specified common carriers can operate. Such LATAs are defined by arbitrary boundaries, generally not corresponding to local exchange or area code boundaries. In addition to the foregoing, certain regions or telephone operating companies impose additional restrictions on numbering plans, such as the use of prefixes 555, 976, 411, 911, 1-800, 1-900, 1-700, etc.
Traditionally, smart telephones are provided with internally programmed structures to carry out telephone calls, and the appropriate nuances to complete such calls. Because of all the noted regulatory and self-imposed restrictions, such smart telephones must be individually programmed to address such nuances. The disadvantage of such an approach is that the telephones must be specially and permanently programmed during manufacture, and sold for use within certain geographical locations. It is apparent that in view of the regulatory and self-imposed restrictions, the extent to which the smart type of telephone can be efficiently manufactured and sold is becoming limited.
From the foregoing, it can be seen that a need exists for an improved telephone which is line powered, but in which essential circuit can operate during certain on-hook conditions. There is an additional need for a smart telephone which can be manufactured without regard to the geographical area in which it is to operate, or at least field programmable to consider changes or modifications as the need arises. A further need exists for a telephone which can be remotely programmed after it has been installed in its intended area of operation, by an individual owner, a distributor or an operator service provider. Because of the extensive use and programming apparatus available, there is a need for a highly secure method of achieving access by authorized persons to the telephone programming circuits.